Journal of Animal and Feed Sciences, 14, Suppl. 1, 2005, 529–532
Effect of dietary CLA isomers on selenium, zinc, copper, chromium, magnesium and calcium levels in rat liver* M. Czauderna1,4, J. Kowalczyk1, E. Bulska2, K. Boldižarova3, K.M. Niedźwiedzka1, A. Ruszczyńska2 and Ľ. Leng3 The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences 05-110 Jabłonna, Poland 2 Faculty of Chemistry, Warsaw University Pasteura 1, 02-093 Warsaw, Poland 3 Institute of Animal Physiology, Slovak Academy of Sciences 0 40 01 Košice, Slovak Republic
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ABSTRACT The effects of diets enriched with 1-2% conjugated linoleic acid isomers (CLA) and/or 2 ppm selenium (as Na2SeO4) on the level of Se, Zn, Cu, Cr, Mg and Ca in the rat liver were studied. Feeding selenium (Se) and/or CLA isomers resulted in significant changes or trends changing the level of Zn, Cu, Cr, Mg and Ca in the liver. The dosage of Se, regardless of the presence of CLA isomers, significantly increased the Se level in the liver. Trans10cis12CLA in the diet most efficiently elevated Zn, Cu, Mg and Ca levels, and, numerically, the Cr content in the liver. KEY WORDS: Se, Zn, Cu, Cr, Mg, Ca, CLA, interactions, liver, rat
INTRODUCTION Numerous beneficial effects on health have been attributed to conjugated linoleic acid (CLA) isomer in view of the anticarcinogenic, antiatherosclerotic, antidiabetogenic and antiadipogenic properties ascribed to them (Belury, 2002; Lavillonniere et al., 2003). The predominant isomer in food is the cis9trans11CLA (c9t11 CLA), followed by t7c9 CLA, 11,13CLA (ct/tc), 8,10CLA (ct/tc) and t10c12 CLA isomer. On the other hand, selenium (Se), an essential trace element for mammals, has been found to be an integral part of the active site of cytosolic Supported by the State Committee for Scientific Research, Grant No. 3 PO6Z 034 22 and by Project VEGA 2/3066/23 4 Corresponding author: e-mail:
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DIETARY CLA-MICROELEMENTS IN RAT’S LIVER
and mitochondrial glutathione peroxidases (cGPx), as well as phospholipid hydroperoxide glutathione peroxidase (PHGPx) (Czauderna et al., 2004). These enzymes reduce hydrogen peroxides, organic hydroperoxides, protecting tissues and polyunsaturated fatty acids (PUFA) in particular, from peroxidation damage. Moreover, it is well established that dietary selenate leads to increasing the CLA content in the rat liver. Therefore, the principal objective of this study was to examine the effect of feeding CLA on the level of Se, Zn, Cu, Cr, Mg and Ca in rat liver. The mechanism of the interaction between CLA and the assayed elements was considered. Rats were used as a model of monogastric animals. MATERIAL AND METHODS Ten groups of 7 female rats each (Wistar, Ifz: BOA), 8 weeks of age and an initial body mass ~200 g were housed individually as described previously (Czauderna et al., 2004). Rats were fed Labofeed ad libitum or diets enriched in CLA isomers and/or 2 ppm Se (as Na2SeO4) (Table 1). After 28 days the rats were killed by CO2 and their livers removed, weighed and freeze-dried. The Se level in the livers was analysed by the fluorimetric method of Rodriguez et al. (1994), while Zn, Cu, Cr, Mg and Ca contents by CPI-MS (Czauderna et al., 2004). The effects of CLA isomers or Se treatments were subjected to statistical analysis by the nonparametric Mann-Whitney U test, while those of the combined Se and CLA treatments, by two-factorial analysis. The Statistica (version 6) and Excel 2000 programs were used. RESULTS AND DISCUSSION Feeding diets enriched in CLA isomers and/or Se resulted in changes of the assayed elements in the liver (Table 1). No lesion or symptoms of Se or CLA isomer intoxication were found. It was found that diets with only CLA isomers (Groups 3-6) resulted in significant (P
